Spinal facet cage implant

ABSTRACT

Implementations described and claimed herein provide a spinal facet cage implant for implantation in a spinal facet joint. In one implementation, the implant includes a distal leading end, a proximal trailing end, a first face, and a second face. The distal leading end has a distal surface generally opposite a proximal surface of the proximal trailing end. The first face has a first surface that is generally parallel with a second surface of the second face. The first and second faces extend between the distal leading end and the proximal trailing end. The first and second surfaces having one or more textured features adapted to provide friction with the spinal facet joint. One or more windows are defined in the first and/or second surfaces, and one or more side windows are defined in the first and/or second side surfaces.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S.application Ser. No. 15/149,781, which was filed on May 9, 2016, whichissued Jan. 8, 2019 as U.S. Pat. No. 10,172,721, which is a continuationof U.S. application Ser. No. 14/037,198, which was filed Sep. 25, 2013and entitled “Spinal Facet Cage Implant”, which issued May 10, 2016 asU.S. Pat. No. 9,333,086, and which claims priority under 35 U.S.C. § 119to U.S. provisional patent application 61/705,365, which was filed Sep.25, 2012; and entitled “Spinal Facet Cage Implant” to U.S. provisionalpatent application 61/777,751, which was filed Mar. 12, 2013 andentitled “Spinal Facet Cage Implant” and to U.S. provisional patentapplication 61/815,977 filed Apr. 25, 2013 and entitled “Cage DeliverySystem” and is a continuation-in-part of U.S. patent application Ser.No. 13/614,372, filed Sep. 13, 2012, which issued Jun. 17, 2014 as U.S.Pat. No. 8,753,377, which is a continuation of U.S. patent applicationSer. No. 12/653,283, filed Dec. 10, 2009, which issued Apr. 23, 2013 asU.S. Pat. No. 8,425,558, which is a continuation-in-part of Ser. No.12/455,814, filed Jun. 5, 2009, which issued Jan. 23, 2013 as U.S. Pat.No. 8,361,152, which claims the benefit of U.S. provisional patentapplication Ser. No. 61/169,601, filed Apr. 15, 2009, and is acontinuation-in-part of U.S. patent application Ser. No. 12/317,682,filed Dec. 23, 2008, which issued Sep. 18, 2012 as U.S. Pat. No.8,267,966, which claims the benefit of U.S. provisional patentapplication Ser. No. 61/109,776, filed Oct. 30, 2008, and U.S.provisional patent application Ser. No. 61/059,723, filed Jun. 6, 2008.

The present application is a continuation application of U.S.application Ser. No. 14/037,198, which was filed Sep. 25, 2013 andentitled “Spinal Facet Cage Implant”, which claims priority to and is acontinuation-in-part of U.S. patent application Ser. No. 13/614,372filed on Sep. 13, 2012, and entitled Vertebral Joint Implants AndDelivery Tools. U.S. patent application Ser. No. 13/614,372 is acontinuation of U.S. patent application Ser. No. 12/653,283, which wasfiled on Dec. 10, 2009, now U.S. Pat. No. 8,425,558, and entitled“Verbal Joint Implants and Delivery Tools.” U.S. patent application Ser.No. 12/653,283 claims priority to and is a continuation-in-part of U.S.patent application Ser. No. 12/455,814, which was filed on Jun. 5, 2009,now U.S. Pat. No. 8,361,152 and entitled “Facet Joint Implants andDelivery Tools.” U.S. patent application Ser. No. 12/455,814 claimspriority to and is a continuation-in-part of U.S. patent applicationSer. No. 12/317,682, which was filed on Dec. 23, 2008, now U.S. Pat. No.8,267,966, and entitled “Facet Joint Implants and Delivery Tools.”

U.S. patent application Ser. No. 12/455,814 further claims priorityunder 35 U.S.C. § 119 to U.S. provisional patent application 61/169,601,which was filed on Apr. 15, 2009 and entitled “Facet Joint Implants andDelivery Tools.”

U.S. patent application Ser. No. 12/317,682 claims priority under 35U.S.C. § 119 to U.S. provisional patent application 61/109,776, whichwas filed Oct. 30, 2008 and entitled “Facet Joint Implants,” and U.S.provisional patent application 61/059,723, which was filed on Jun. 6,2008 and entitled “Spine Distraction Device.”

Each of the aforementioned applications is hereby incorporated byreference in its entirety into the present application.

TECHNICAL FIELD

Aspects of the present disclosure relate to a device for distracting thespine and more particularly to a tool for distracting a facet joint ofthe spine and an implant for maintaining the distracted position of thejoint.

BACKGROUND

Chronic back problems cause pain and disability for a large segment ofthe population. Adverse spinal conditions may be characteristic of age.In particular, spinal stenosis (including, but not limited to, central,canal, and lateral stenosis) and facet arthropathy may increase withage. Spinal stenosis results in a reduction of foraminal area (i.e. theavailable space for the passage of nerves and blood vessels), which maycompress cervical nerve roots and cause radicular pain. Both neckextension and ipsilateral rotation, in contrast to neck flexion, mayfurther reduce the foraminal area and contribute to pain, nerve rootcompression, and neural injury.

Cervical disc herniations may be a factor in spinal stenosis and maypredominantly present upper extremity radicular symptoms. In this case,treatment may take the form of closed traction. A number of closedtraction devices are available that alleviate pain by pulling on thehead to increase foraminal height. Cervical disc herniations may also betreated with anterior and posterior surgery. Many of these surgeries areperformed through an anterior approach, which requires a spinal fusion.These surgeries may be expensive and beget additional surgeries due tochanging the biomechanics of the neck. There is a three percentincidence of re-operation after cervical spine surgery. Moreover, thesesurgeries may be highly invasive leading to long recovery times.

There is a need in the art for implants, delivery systems, and methodsof implantation that facilitate the fusion of a spinal facet joint via aminimally invasive or percutaneous procedure from, for example, aposterior approach.

It is with these observations in mind, among others, that variousaspects of the present disclosure were conceived and developed.

SUMMARY

Implementations described and claimed herein address the foregoingproblems, among others, by providing a spinal facet cage implant forimplantation in a spinal facet joint. In one implementation, the implantincludes a distal leading end, a first face, and a first side. Thedistal leading end has a distal surface generally opposite a proximalsurface of a proximal trailing end. The first face has a first surfacethat is generally parallel with a second surface of a second face. Thefirst and second faces extend between the distal leading end and theproximal trailing end. The first and second surfaces having one or moretextured features adapted to provide friction with the spinal facetjoint. The first side has a first side surface generally opposite asecond side having a second side surface. One or more windows aredefined in the first surface generally opposing one or more windowsdefined in the second surface, and one or more side windows are definedin the first side surface generally opposing one or more windows definedin the second side surface, the windows and side windows providingaccess to a hollow interior of the implant.

Other implementations are also described and recited herein. Further,while multiple implementations are disclosed, still otherimplementations of the presently disclosed technology will becomeapparent to those skilled in the art from the following detaileddescription, which shows and describes illustrative implementations ofthe presently disclosed technology. As will be realized, the presentlydisclosed technology is capable of modifications in various aspects, allwithout departing from the spirit and scope of the presently disclosedtechnology. Accordingly, the drawings and detailed description are to beregarded as illustrative in nature and not limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-F are front isometric, rear isometric, side, top plan, distalleading end, and proximal trailing end views, respectively, of anexample spinal facet cage implant.

FIG. 1G is a transverse isometric elevation cross section of the implantof FIGS. 1A-D, as taken along section line G shown in FIG. 1A.

FIG. 1H is a longitudinal isometric elevation cross section of theimplant of FIGS. 1A-D, as taken along section line H shown in FIG. 1A.

FIG. 1-1 is a transverse isometric plan cross section of the implant ofFIGS. 1A-D, as taken along section line I shown in FIG. 1A.

FIG. 1J is a transverse isometric elevation cross section of the implantof FIGS. 1A-D, as taken along section line J shown in FIG. 1A.

FIGS. 2A-F are front isometric, rear isometric, side, top plan, distalleading end, and proximal trailing end views, respectively, of anotherexample spinal facet cage implant.

FIGS. 3A-D show front isometric, top plan, proximal trailing end, andside views, respectively, of an example spinal facet cage implantincluding textured faces having small pyramids.

FIGS. 4A-D show isometric, top plan, proximal trailing end, and sideviews, respectively, of an example spinal facet cage implant includingtextured faces having large pyramids.

FIGS. 5A-D are isometric, top plan, proximal trailing end, and sideviews, respectively, of an example spinal facet cage implant includingtextured faces having dimples.

FIGS. 6A-D show isometric, top plan, proximal trailing end, and sideviews, respectively, of an example including textured faces having grit.

FIGS. 7A-D depict isometric, top plan, proximal trailing end, and sideviews, respectively, of an example spinal facet cage implant includingtextured faces having pits.

FIGS. 8A-D show isometric, top plan, proximal trailing end, and sideviews, respectively, of an example spinal facet cage implant includingtextured faces having pyramids.

FIG. 9 shows an example delivery device and guide tube configured tominimally invasively deliver a spinal facet cage implant.

FIG. 10 shows a perspective view the delivery device of FIG. 9 and adetailed view of a distal end of the delivery device.

FIG. 11A illustrates a perspective view of the guide tube of FIG. 9,wherein the distal end of the guide tube has same-sized parallel prongs.

FIG. 11B is an enlarged longitudinal side view of an alternativeembodiment of the distal end of the guide tube having dual-sizedparallel prongs.

FIG. 12 depicts a perspective view of an example decorticator.

FIG. 13 shows a perspective view of an example injector.

FIG. 14 is a perspective view of an example chisel.

FIG. 15 illustrates an example place holding chisel.

FIG. 16 depicts a perspective view of an example malleting tool.

FIGS. 17-18 outline a method of implanting the implant in a spinal facetjoint space.

FIG. 19A is a side view of a place holding or access chisel.

FIG. 19B is an enlarged perspective view of a distal portion of thechisel of FIG. 19A.

FIG. 20 is a side view of the chisel of FIG. 19A extending through and aguide tube or tool.

FIG. 21 is a side view of the guide tool of FIG. 20.

FIG. 22 is a side view of a decorticating chisel with a rasp end beingintroduced into a proximal end of the guide tool of FIG. 21.

FIG. 23 is a side view of the decorticating chisel of FIG. 22 fullyinserted in the guide tool, wherein the devices so coupled together canbe considered to form a driver assembly.

FIGS. 24 and 25 are perspective views of various distal tip portions ofthe decorticating chisel positioned between distal spaced-apart forks ofthe distal end of the guide tool.

FIG. 26 is a side view of a driver device or delivery tool supportingthe implant from a distal end of the delivery tool, the delivery toolbeing positioned to be inserted in a proximal portion of the guide tool.

FIG. 27 is a side view of the driver device fully received in the guidetool.

FIG. 28 is an enlarged perspective view of a distal end of the driverdevice, wherein a threaded male member is visible for threadablycoupling with the implant.

FIG. 29 is a perspective view of the implant wherein a threaded femaleopening is depicted in a proximal face of the implant.

FIG. 30 is a perspective view of the distal end of the driver assemblyapproaching the proximal end of the implant to achieve coupling betweenthe two.

FIG. 31 is a perspective view of the distal end of the driver assemblycoupled to the proximal end of the implant.

FIG. 32 is a perspective view of the guide tool, driver assembly, andimplant wherein the implant is coupled to the distal end of the driverassembly and nestled between the forks of the guide tool.

FIG. 33 is the same view as FIG. 32, except the driver assembly has beendecoupled from the implant and withdrawn from within the guide tube.

FIGS. 34 and 35 are longitudinal cross sections of the arrangementdepicted in FIG. 32.

FIG. 36 shows a perspective view of a proximal or trailing end of animplant.

DETAILED DESCRIPTION

Aspects of the present disclosure generally involve devices and methodsfor treating spinal stenosis. Spinal stenosis reflects a narrowing ofone or more areas of the spine often in the upper or lower back. Thisnarrowing can put pressure on the spinal cord or on the nerves thatbranch out from the compressed areas. Individual vertebrae of the spineare positioned relative to each other and their separation is maintainedby discs separating main vertebral bodies and by capsules positionedwithin facet joints. The discs and capsules are separated from the boneof their respective joints by cartilage. Spinal stenosis is oftenindicative of degeneration of a disc, a capsule, or the cartilage in ajoint, which leads to a compression of the joints and the narrowingmentioned.

As such, in one aspect, a device for distracting a facet joint of thespine is provided to remedy this condition. The device may include atool and an implant for distracting and maintaining the distractedposition of the joint. The device may be adapted to access a facet jointby inserting a delivery tool and an implant, forcibly separate theassociated articular surfaces with the tool, the implant, or both, andleave the implant in place to maintain the separation of the articularsurfaces. This approach may allow for maintaining the distraction of thejoint, thereby relieving symptoms associated with spinal stenosis.

In one particular aspect, a spinal facet cage implant sized for use as acervical cage implant for implantation in a spinal facet joint to bringabout the fusion of the spinal facet joint is provided. The implantincludes at least one face having textured features that providesfriction between the spinal facet joint and the implant and one or morewindows to place a hollow interior of the implant in communication withthe surrounding environment.

For a detailed description of an example spinal facet cage implant 100,reference is made to FIGS. 1A-F, which are front isometric, rearisometric, side, top plan, distal leading end, and proximal trailing endviews, respectively.

The implant 100 may be formed of a bone or bone substitute material or abiocompatible metal, ceramic, polymer, or some combination thereof. Inone implementation, the implant 100 includes a distal leading end 102generally opposite a proximal trailing end 104, a first face 106generally opposite a second face 108, and a first side 110 generallyopposite a second side 112. In one implementation, the implant 100 has ageneral overall shape of a rectangular box with one or more texturedfeatures 114.

The first face 106 extends between the distal leading end 102 and theproximal trailing end 104. In one implementation, the first face 106 isgenerally parallel with the second face 108. For example, the first face106 may extend from the distal leading end 102 to the proximal trailingend 104 at an angle of approximately 0° to 15° relative to the secondface 108. As such, a height of the proximal trailing end 104 may begreater than or equal to a height of the distal leading end 102. In oneimplementation, the first and second faces 106 and 108 include thetextured features 114 that provide friction between the spinal facetjoint and the implant 100.

In the implementation shown in FIGS. 1A-F, the distal leading end 102includes a distal surface 116 and the proximal trailing end 104 includesa proximal surface 118. In one implementation, the distal and proximalsurfaces 116 and 118 are planar surfaces forming a generally rectangularshape. The distal surface 116 includes a first pair of distal edges 128extending between the first and second sides 110 and 112 and a secondpair of distal edges 134 extending between the first and second faces106 and 108. Similarly, the proximal surface 118 includes a first pairof proximal edges 128 and a second pair of proximal edges 120 extendingbetween the first and second faces 106 and 108. In one implementation,where the height of the proximal trailing end 104 is greater than theheight of the distal leading end 102, the height of the second pair ofproximal edges 120 is greater than the height of the second pair ofdistal edges 134, such that a surface 124 of the first face 106 and asurface 130 of the second face 108 slope upwardly from the distalleading end 102 to the proximal trailing end 104 along a length 140extending proximally.

In one implementation, the surface 124 of the first face 106 and thesurface 130 of the second face 108 are planar surfaces having agenerally rectangular shape formed from the length 140 and a width thatis generally coextensive with the first pair of edges 128. The first andsecond sides 110 and 112 each include a side surface 132 extendingbetween the distal leading end 102 and the proximal trailing end 104. Inone implementation, the side surface 132 is a generally planar surfacehaving a pair of opposed edges that are generally coextensive with thesecond pair of distal edges 134 and the second pair of proximal edges120.

In one implementation, one or more windows or openings (e.g. a firstwindow 136 and a second window 138) are defined in the surface 124 ofthe first face 106. The first and second windows 136 and 138 may beopposed or otherwise defined relative to respective windows defined inthe surface 130 of the second face 108. Similarly, the first and secondsides 110 and 112 may each have one or more windows or openings (e.g., afirst side window 122 and a second side window 126) defined in the sidesurface 132. In one implementation, the windows 122, 126, 136, and 138each are adapted to place a hollow interior of the implant 100 incommunication with the surrounding environment. The windows 122, 126,136, and 138 may be any shape, size, number, and orientation. Forexample, in one implementation, the first and second windows 136 and 138are each generally rectangular and oriented end-to-end, such that eachof the windows 136 and 138 extends along approximately half of thelength 140 and centered along the edges 128. Similarly, the first andsecond side windows 122 and 126 are each generally rectangular andoriented end-to-end, such that each of the windows 122 and 126 extendsalong approximately half of the length 140 and centered along the edges134 and 120. In one implementation, the first and second windows 136 and138 are larger in size than the first and second side windows 122 and126.

The surface 124 of the first face 106 and/or the surface 130 of thesecond face 108 include the textured features 114. In the implementationshown in FIGS. 1A-F, the textured features 114 are one or more ridgesextending generally perpendicularly from the surfaces 124 and/or 130along the length 140. Each of the ridges includes an inner surface 142generally opposite an outer surface 144. In one implementation, theouter surface 144 of each of the ridges is generally planar andcoextensive with the side surface 132, and the inner surface 142 of eachof the ridges is a generally planar surface that is generallyperpendicular to the surface 124 of the first face 106 and/or thesurface 130 of the second face 108. In one implementation, each of theridges has a saw toothed profile defined by a plurality of teeth havinga leading distal face 148, a trailing proximal face 150, and a tip 146formed at an intersection between the faces 148 and 150. The trailingproximal face 150 has a slope that is different from a slope of theleading distal face 148. For example, the trailing proximal face 150 hasa slope that is greater than the slope of the leading distal face 148.In one implementation, the slope of the trailing proximal face 150 isapproximately 90°.

Further, the height of the tips 146 may increase along the length 140,such that teeth positioned near the proximal trailing end 104 have agreater height than teeth positioned near the distal leading end 102.Additionally, a distance between each of the teeth may vary along thelength 140. For example, the distance between the teeth positioned nearthe distal leading end 102 may be less than the distance between theteeth positioned near the proximal trailing end 104. The tip 146 may bea truncated flat surface, a point, or other shapes. Further, it will beappreciated that the first and second faces 106 and 108 may include anynumber or configuration of ridges or teeth and that the texturedfeatures 114 may cover all or a portion of the surface 124 of the firstface 106 and/or the surface 130 of the second face 108.

As can be understood from FIGS. 1G-J, in one implementation, the hollowinterior of the implant 100 includes one or more chambers 152. Forexample, the hollow interior may include a chamber 152 separated into adistal chamber and a proximal chamber by an interior wall 154. In thiscase, the windows 136 and 122 near the distal leading end 102 may be incommunication with the distal portion of the chamber 152, and thewindows 138 and 126 near the proximal trailing end 104 may be incommunication with the proximal portion of the chamber 152. The chambers152 may, via the windows 122, 126, 136, and 138, be packed with a boneor bone substitute material for causing bone ingrowth into a hollowvolume of the chambers 152.

The implant 100 may be a variety of configurations and sizes. In oneimplementation, the implant 100 has one degree deviation between thefirst and second faces 106 and 108 and is sized accordingly. Forexample, a width W1 of the implant 100 extending along the edges 128between the opposing side surfaces 132 may be approximately 0.217inches, and a width W2 of the implant 100 extending along the edges 128between opposing textured features 114 may be approximately 0.177inches. Additionally, a height H1 from the surface 124 of the first face106 to the surface 130 of the second face 108 may be approximately 0.118inches, and a height H2 from a tip 146 of a tooth positioned on thesurface 124 to a respective tip 146 positioned on the surface 130 may beapproximately 0.187 inches. Further, a length of the teeth LT along thelength 140 may be approximately 0.039 inches, and a height HT from arelative surface 124, 130 to the tip 146 may be approximately 0.029inches. A length LI of the implant 100 extending along the length 140from the distal leading end 102 to the proximal trailing end 104 may beapproximately 0.472 inches. Further, a length LW of the windows 136 and138 along the length 140 may be approximately 0.177 inches, a width WWof the windows 136 and 138 along the edges 128 may be approximately 0.10inches, and a distance D of the window 136 from the distal surface 116may be approximately 0.039 inches. However, it will be appreciated thatother sizes an configurations are contemplated where the implant 100 hasone degree of deviation between the faces 106, 108.

In another implementation, the implant 100 has three degrees deviationbetween the first and second faces 106 and 108 and is sized accordingly.For example, a width W1 of the implant 100 extending along the edges 128between the opposing side surfaces 132 may be approximately 0.217inches, and a width W2 of the implant 100 extending along the edges 128between opposing textured features 114 may be approximately 0.177inches. Additionally, a height H1 from the surface 124 of the first face106 to the surface 130 of the second face 108 may be approximately 0.103inches, and a height H2 from a tip 146 of a tooth positioned on thesurface 124 to a respective tip 146 positioned on the surface 130 may beapproximately 0.187 inches. Further, a length LT of the teeth along thelength 140 may be approximately 0.040 inches, and a height HT from arelative surface 124, 130 to the tip 146 may be approximately 0.030inches. A length LI of the implant 100 extending along the length 140from the distal leading end 102 to the proximal trailing end 104 may beapproximately 0.472 inches. Further, a length LW of the windows 136 and138 along the length 140 may be approximately 0.177 inches, a width WWof the windows 136 and 138 along the edges 128 may be approximately0.098 inches, and a distance D of the window 136 from the distal surface116 may be approximately 0.039 inches. However, it will be appreciatedthat other sizes an configurations are contemplated where the implant100 has three degrees of deviation. Further, other deviations betweenthe first and second faces 106 and 108 for the implant 100 may beanywhere between approximately 0° to 15°.

In one implementation, one or both of the first and second faces 106 and108 may be arcuate as opposed to planar. Stated differently, thesurfaces 124 and/or 130 may be arched or planar. For example, a width W1of the implant 100 extending along the edges 128 between the opposingside surfaces 132 may be approximately 0.217 inches, and a length LI ofthe implant 100 extending along the length 140 from the distal leadingend 102 to the proximal trailing end 104 may be approximately 0.472inches. Additionally, a height H1 from the surface 124 of the first face106 to the surface 130 of the second face 108 may be approximately 0.127inches, and a height H2 from a tip 146 of a tooth positioned in theapproximate center of the length 140 (e.g., at a maximum of the arch orbulge) on the surface 124 to a respective tip 146 positioned on thesurface 130 may be approximately 0.226 inches. Further, a length LT ofthe teeth along the length 140 may be approximately 0.039 inches, and aheight HT from a relative surface 124, 130 to the tip 146 may beapproximately 0.030 inches. Additionally, a length LW of the windows 136and 138 along the length 140 may be approximately 0.177 inches, a widthWW of the windows 136 and 138 along the edges 128 may be approximately0.098 inches, and a distance D of the window 136 from the distal surface116 may be approximately 0.039 inches. However, it will be appreciatedthat other sizes an configurations are contemplated where the implant100 has arcuate surfaces.

The implant 100 may have a variety of sizes that lend itself to acervical implant. For example, in one implementation, the implant 100may have a seven degree deviation between the first and second faces 106and 108. For example, a width W1 of the implant 100 extending along theedges 128 between the opposing side surfaces 132 may be approximately0.217 inches, and a length LI of the implant 100 extending along thelength 140 from the distal leading end 102 to the proximal trailing end104 may be approximately 0.472 inches. A height H1 from the surface 124of the first face 106 to the surface 130 of the second face 108 may beapproximately 0.098 inches at the distal leading end 102 andapproximately 0.157 inches at the proximal trailing end 104. Further, alength LW of the windows 136 and 138 along the length 140 may beapproximately 0.177 inches, a width WW of the windows 136 and 138 alongthe edges 128 may be approximately 0.098 inches, and a distance D of thewindow 136 from the distal surface 116 may be approximately 0.039inches. A length LWS of the windows 122 and 126 along the length 140 maybe approximately 0.177 inches, a width WWS of the windows 122 and 126along the edges 128 may be approximately 0.049 inches, and a distance DSof the window 122 from the distal surface 116 may be approximately 0.039inches. Further, a height HT of a tip 146 of a tooth positioned on thesurface 124 or 130 to may be approximately 0.029 inches, and a heightfrom a tip 146 of a tooth positioned in near the proximal trailing end104 on the surface 124 to a respective tip 146 positioned on the surface130 may be approximately 0.216 inches. Additionally, a distance from onetip 146 to a proximally neighboring tip 146 along the length 140 mayincrease proximally, for example, 0.039 inches to a first tip 146, 0.111inches to a second, 0.183 inches to a third, 0.255 inches to a fourth,0.328 inches to a fifth, 0.400 inches to a sixth, and 0.472 inches to aseventh. However, it will be appreciated that other sizes anconfigurations are contemplated where the implant 100 has seven degreesof deviation. For example, a height from the surface 124 of the firstface 106 to the surface 130 of the second face 108 may have a +/−0.15inch deviation, and a length of the implant 100 extending along thelength 140 from the distal leading end 102 to the proximal trailing end104 may have a +/−0.15 inch deviation.

For additional examples of the implant 100 with various texturedfeatures 114 and windows configurations, reference is made to FIGS.2A-8D. The implants 100 illustrated in FIGS. 2A-8D have features similarto the implant 100 described with respect to FIGS. 1A-J. It will beappreciated that other configurations are contemplated and theseillustrations are exemplary and not intended to be limiting.

Turning to FIGS. 2A-D, in one implementation, the surface 124 of thefirst face 106 and/or the surface 130 of the second face 108 include thetextured features 114. In one implementation, the textured features 114are a plurality of serrated ridges extending across each of the surfaces124 and 130 generally perpendicularly from the surfaces 124 and/or 130along the length 140. Each of the ridges includes the outer surface 144,which is generally planar and coextensive with the side surface 132. Inone implementation, each of the ridges has a saw toothed profile definedby a plurality of teeth having a leading distal face 200, a trailingproximal face 204, and a tip 202 formed at an intersection between thefaces 200 and 204. The trailing proximal face 204 has a slope that isdifferent from a slope of the leading distal face 200. For example, thetrailing proximal face 204 has a slope that is greater than the slope ofthe leading distal face 200. In one implementation, the ridges aresubstantially evenly spaced.

In contrast to the implementation shown in FIGS. 1A-J, the windows 136and 138 shown in FIGS. 2A-D are generally circular in shape and aredefined in the surface 124 and/or 130 and the ridges. Further, in oneimplementation, the proximal surface 118 includes a hole 210 definedtherein for coupling to a delivery tool (e.g., the tool shown in FIGS.9-16).

Turning to FIGS. 3A-D, the surface 124 of the first face 106 and/or thesurface 130 of the second face 108 include the textured features 114. Inone implementation, the textured features 114 are a plurality ofprotrusions 300 extending generally perpendicularly from the surfaces124 and/or 130 along the length 140. In the implementation shown inFIGS. 3A-D, the protrusions 300 have a pyramidal shape, including fourgenerally triangular faces and a rectangular base that is generallyparallel to the respective surfaces 124 and/or 130. The rectangular baseforms generally right angles that are coextensive with angles formed bythe width 126 and the length 140 of the respective surfaces 124 and/or130. Each face of the protrusions 300 is adjacent to two other faces ofthe same protrusion 300 that extend outwardly from the respectivesurfaces 124 and/or 130 where they adjoin to form a tip. The protrusions300 shown in FIGS. 3A-D are relatively small pyramids.

In one implementation, the protrusions 300 are arranged in rows, suchthat the rectangular base of each of the protrusions 300 abut the basesof adjacent protrusions 300. A plurality of the protrusions 300 extendfrom the first side 110 to the second side 112 to form the rows, and therows, in turn, extend from the distal leading end 102 to the proximaltrailing end 104 to form a series of rows with the windows 136 and 138defined therein. Further, it will be appreciated that the first andsecond faces 106 and 108 may include any number or configuration of theprotrusions 300 and that the textured features 114 may cover all or aportion of the surface 124 of the first face 106 and/or the surface 130of the second face 108.

In one implementation, the proximal surface 118 includes a hole 210defined therein for coupling to a delivery tool (e.g., the tool shown inFIGS. 9-16) and a pair of cylindrical pegs 302 with rounded edges.Further, the interior wall 154 may have the hole 210 defined thereinhaving a centerline that is coextensive with a centerline of the hole210 defined in the proximal surface 118. In one implementation, the hole210 is generally centered on the proximal surface 118 and the pegs 302generally oppose each other on either side of the hole 210.

Turning to FIGS. 4A-D, in one implementation, the surface 124 of thefirst face 106 and/or the surface 130 of the second face 108 include thetextured features 114. In one implementation, the textured features 114are a plurality of protrusions 400 extending generally perpendicularlyfrom the surfaces 124 and/or 130 along the length 140. In theimplementation shown in FIGS. 4A-D, the protrusions 400 have a pyramidalshape, including four generally triangular faces and a rectangular basethat is generally parallel to the respective surfaces 124 and/or 130.The rectangular base forms generally right angles that are coextensivewith angles formed by the width 126 and the length 140 of the respectivesurfaces 124 and/or 130. Each face of the protrusions 400 is adjacent totwo other faces of the same protrusion 400 that extend outwardly fromthe respective surfaces 124 and/or 130 where they adjoin to form a tip.The protrusions 400 shown in FIGS. 4A-D are relatively large pyramids.

In one implementation, the protrusions 400 are arranged in rows, suchthat the rectangular base of each of the protrusions 400 abut the basesof adjacent protrusions 400. There may be a gap between each of the rowsto accommodate larger protrusions 400. A plurality of the protrusions400 extend from the first side 110 to the second side 112 to form therows, and the rows, in turn, extend from the distal leading end 102 tothe proximal trailing end 104 to form a series of rows with the windows136 and 138 defined therein. Further, it will be appreciated that thefirst and second faces 106 and 108 may include any number orconfiguration of the protrusions 400 and that the textured features 114may cover all or a portion of the surface 124 of the first face 106and/or the surface 130 of the second face 108.

In one implementation, the proximal surface 118 includes a hole 210defined therein for coupling to a delivery tool (e.g., the tool shown inFIGS. 9-16) and the pair of cylindrical pegs 302 with rounded edges.Further, the interior wall 154 may have the hole 210 defined thereinhaving a centerline that is coextensive with a centerline of the hole210 defined in the proximal surface 118. In one implementation, the hole210 is generally centered on the proximal surface 118 and the pegs 302generally oppose each other on either side of the hole 210.

As can be understood from FIGS. 5A-D, the surface 124 of the first face106 and/or the surface 130 of the second face 108 include the texturedfeatures 114 defined therein. In one implementation, the texturedfeatures 114 are a plurality of dimples 500 having a generally sphericalimprint or indentation 502 having a radial depth generallyperpendicularly into the respective surfaces 124 and/or 130. In oneimplementation, the dimples 500 are arranged in rows, such that theindentations 502 overlap with at least a portion of an adjacentindentation 502. A plurality of the dimples 500 extend from the firstside 110 to the second side 112 to form the rows, and the rows, in turn,extend from the distal leading end 102 to the proximal trailing end 104to form a series of rows with the windows 136 and 138 defined therein.The effect creates a grid-like pattern of the dimples 500 forming towers504 between the indentations 502. In one implementation, the towers 504are generally planar surfaces. The degree of overlap of the indentations502 and the depth of the indentations 502 can vary accordingly so as toprovide an appropriate amount of friction and grip between the implant100 and the bone surface. Further, it will be appreciated that the firstand second faces 106 and 108 may include any number or configuration ofthe dimples 500 and that the textured features 114 may cover all or aportion of the surface 124 of the first face 106 and/or the surface 130of the second face 108.

In one implementation, the proximal surface 118 includes a hole 210defined therein for coupling to a delivery tool (e.g., the tool shown inFIGS. 9-16) and the pair of cylindrical pegs 302 with rounded edges.Further, the interior wall 154 may have the hole 210 defined thereinhaving a centerline that is coextensive with a centerline of the hole210 defined in the proximal surface 118. In one implementation, the hole210 is generally centered on the proximal surface 118 and the pegs 302generally oppose each other on either side of the hole 210.

Referring to FIGS. 6A-D, in one implementation, the surface 124 of thefirst face 106 and/or the surface 130 of the second face 108 include thetextured features 114. Further, the side surfaces 124, the distalsurface 116, and/or the proximal surface 118 may include the texturedfeatures 114. In one implementation, the textured features 114 are aplurality of grit particles 600 extending generally perpendicularly fromthe surfaces 124 and/or 130 along the length 140 with the windows 136and 138 defined therein. The grit particles 600 may be a variety ofshapes adapted to fuse the implant 100 to the bone surface. In theimplementation shown in FIGS. 6A-D, the grit particles 700 have asemi-circular, bubble-like shape.

In one implementation, the grit particles 600 are randomly adhered tothe respective surfaces 124 and 130, such that the surfaces 124 and 130may contain differences in the layout of the textured features 114. Thegrit particles 600 may be applied by a variety of suitable means toadhere the grit particles 600 to the material of the surfaces 124 and130. In another implementation, the grit particles 600 are arrangedrelatively uniformly (i.e., in rows or strips) on the respectivesurfaces 124 and 130. Further, it will be appreciated that the first andsecond faces 106 and 108 may include any number or configuration of thegrit particles 600 and that the textured features 114 may cover all or aportion of the surface 124 of the first face 106 and/or the surface 130of the second face 108.

In one implementation, the proximal surface 118 includes a hole 210defined therein for coupling to a delivery tool (e.g., the tool shown inFIGS. 9-16) and the pair of cylindrical pegs 302 with rounded edges.Further, the interior wall 154 may have the hole 210 defined thereinhaving a centerline that is coextensive with a centerline of the hole210 defined in the proximal surface 118. In one implementation, the hole210 is generally centered on the proximal surface 118 and the pegs 302generally oppose each other on either side of the hole 210.

Turning to FIGS. 7A-D, in one implementation, the surface 124 of thefirst face 106 and/or the surface 130 of the second face 108 include thetextured features 114. Further, the side surfaces 124, the distalsurface 116, and/or the proximal surface 118 may include the texturedfeatures 114. In one implementation, the textured features 114 are aplurality of pits 700 extending generally perpendicularly into thesurfaces 124 and/or 130 along the length 140 with the windows 136 and138 defined therein. The pits 700 may be a variety of shapes adapted tofuse the implant to the bone surface. For example, the pits 700 may beshaped like a negative imprint of the grit particles 600, the dimples500, the protrusions 400 or 300 or any similar feature. In theimplementation shown in FIGS. 7A-D, for example, the pits 700 arenegative imprints of a semi-circular, bubble-like shape. The depth ofsuch an imprint and the imprint diameter will vary accordingly toachieve adequate friction between the implant and the bone.

The surfaces 124 and 130 may undergo a reductive surface treatment,including, without limitation, abrasive blasting, chemical treating, andthe like, to achieve the pits 700. In addition to a reductive surfacetreatment, an additive treatment may be used to texture the surfaces 124and 130 to add a pre-textured layer. In one implementation, the pits 800cover the respective surfaces 124 and 130 in a random orientation, suchthat the surfaces 124 and 130 may contain differences in the layout ofthe textured features 114. In another implementation, the pits 700 arearranged relatively uniformly (i.e., in rows or strips) on therespective surfaces 124 and 130. Further, it will be appreciated thatthe first and second faces 106 and 108 may include any number orconfiguration of the pits 700 and that the textured features 114 maycover all or a portion of the surface 124 of the first face 106 and/orthe surface 130 of the second face 108.

In one implementation, the proximal surface 118 includes a hole 210defined therein for coupling to a delivery tool (e.g., the tool shown inFIGS. 9-16) and the pair of cylindrical pegs 302 with rounded edges.Further, the interior wall 154 may have the hole 210 defined thereinhaving a centerline that is coextensive with a centerline of the hole210 defined in the proximal surface 118. In one implementation, the hole210 is generally centered on the proximal surface 118 and the pegs 302generally oppose each other on either side of the hole 210.

Turning to FIGS. 8A-D, in one implementation, the surface 124 of thefirst face 106 and/or the surface 130 of the second face 108 include thetextured features 114. In one implementation, the textured features 114are a plurality of protrusions 800 extending generally perpendicularlyfrom the surfaces 124 and/or 130 along the length 140. In theimplementation shown in FIGS. 8A-D, the protrusions 800 have a pyramidalshape, including four generally triangular faces and a rectangular basethat is generally parallel to the respective surfaces 124 and/or 130.The rectangular base forms generally right angles that are coextensivewith angles formed by the width 126 and the length 140 of the respectivesurfaces 124 and/or 130. Each face of the protrusions 800 is adjacent totwo other faces of the same protrusion 800 that extend outwardly fromthe respective surfaces 124 and/or 130 where they adjoin to form a tip.The protrusions 800 shown in FIGS. 8A-D are relatively small pyramids.

In one implementation, the protrusions 800 are arranged in rows, suchthat the rectangular base of each of the protrusions 800 abut the basesof adjacent protrusions 800. There may be a gap between each of the rowsto accommodate larger protrusions 800. A plurality of the protrusions800 extend from the first side 110 to the second side 112 to form therows, and the rows, in turn, extend from the distal leading end 102 tothe proximal trailing end 104 to form a series of rows covering thesurfaces 124 and 130. Further, it will be appreciated that the first andsecond faces 106 and 108 may include any number or configuration of theprotrusions 800 and that the textured features 114 may cover all or aportion of the surface 124 of the first face 106 and/or the surface 130of the second face 108.

In one implementation, the proximal surface 118 includes a hole 210defined therein for coupling to a delivery tool (e.g., the tool shown inFIGS. 9-16) and the pair of cylindrical pegs 302 with rounded edges. Thehole 210 may be generally centered on the proximal surface 118 and thepegs 302 generally oppose each other on either side of the hole 210. Inone implementation, the implant 100 does not includes the windows 122,126, 136, and/or 138.

As can be understood from FIGS. 9-16, a distraction system 900 isconfigured to minimally invasively or percutaneously deliverimplementations of the implant 100 into a patient spinal facet jointspace via, for example, a posterior approach. In one implementation, thesystem 900 includes a delivery tool 902 and a guide tube 904, both ofwhich extend from a respective leading distal end 906, 907 to arespective trailing proximal end 908, 909. As can be understood fromFIG. 9, the delivery tool 902 can be received in the lumen of the guidetube 904 to bring about the delivery of the implant 100 into the targetspinal facet joint. The system 900 may further include a decorticator936, an injector 948, a chisel 960, a place holding chisel 974, and amalleting tool 980.

For a detailed description of the delivery tool 902, reference is madeto FIG. 10. In one implementation, the delivery tool 902 includes atubular body 910 with a handle arrangement 912 at the trailing proximalend 908. The handle arrangement 912 may further include one or moremembers 914 for engaging the guide tube 904 as depicted in FIG. 9. Inone implementation, a plunger or threaded member 916 extends through alumen 918 of the tubular body 910 and includes a handle 920 at thetrailing proximal end 906. In the case of the plunger embodiment, theplunger may be used to distally push the implant from an interferencefit engagement with the arms 922 of the delivery tool distal end 906. Inthe case of the threaded member embodiment, the threaded member 916threadably engages the implant 100 to retain the implant 100 in anattached manner to the delivery tool distal end 906 until time torelease the implant 100 into the target facet joint space.

In one implementation, the tubular body 910 at the leading distal end906 includes opposed prongs 922 between which the implant 100 may besupported until the plunger 916 can be used to eject the implant 100,or, in the case of a threaded member, until the threaded member 916 canbe threadably uncoupled from the implant 100. The prongs 922 includelongitudinally extending ridges that are adapted to interact with thesides 110 and 112 of the implant 100 or structural features of theimplant 100 (e.g., the windows 122 and/or 126). In one implementation,the plunger 916 is spring biased to keep the plunger 916 proximallydisplaced in the lumen 918 of the tubular body 910, such that distalforce exerted against the handle 920 causes the plunger 216 to distallydisplace to eject the implant from the tubular body 910 at the leadingdistal end 906. In one embodiment where there is the threadedengagement, the threaded member 916 is rotationally displaceable withinand relative to the delivery tool shaft 910.

As discussed herein, in some implementations, the proximal trailing end104 of the implant 100 includes a structural feature (e.g., the threadedhole 210) that may be engaged by a retainer member (e.g., a threaded rod916) extending through the lumen 918 of the tubular body 910 to retainthe implant 100 at the distal end 906 of the tubular body 910 until theretainer member can be disengaged to allow the implant 100 to be leftbehind in the facet joint upon the tubular body 910 being withdrawn fromthe percutaneous access site.

Turning to FIG. 11A, a detailed description of the guide tube or tool904 is provided. In one implementation, the guide tube 904 includes areceiving assembly 926 at a proximal end 909 and a pair of anchoringforks 934 at a distal end 907 with a generally tubular shaft 924extending there between. The anchoring forks 934 may be textured distalparallel prongs for accessing a spinal facet joint and through which thedelivery tool 902 can be routed to deliver the implant 100 in the facetjoint. As illustrated in FIG. 11A, in one embodiment, the two parallelprongs 934 may have the same height and configuration, differing only inthat they are mirror images of each other. In another embodiment, thetwo parallel prongs 934 may differ in height relative to each other,thereby distracting the facet joint at different heights at each pronginterface with the facet joint. For example, as illustrated in FIG. 11B,which is an enlarged longitudinal side view of an alternative embodimentof the distal end of the guide tube having dual-sized parallel prongs,the two parallel prongs may have heights HP1 and HP2 of 0.106 inches and0.164 inches. However, other dimensions of the guide tube 904 arecontemplated.

The guide tube 904 can also include a malleting anvil 930 having araised surface 932 positioned on the proximal face of the receivingassembly 926 adapted for contact with a distal end of a malleting head966 on the chisel 960 or on the delivery tool 902. Malleting on theproximal end of the chisel 960 or the delivery tool 902 can causelongitudinal forces along the length of the respective tool piece. Theselongitudinal forces can be transferred, at least partially, through thecontact between the malleting head and the malleting anvil 930.Accordingly, relative motion between the respective tool piece and theguide tube 904 can be prevented. As such, for example, at the distal end907 of the guide tube 904, the relative position of the distal end 972of the chisel 960 or the delivery tool 902 relative to the distal end907 of the guide tube 904 can be maintained. Further, in oneimplementation, the receiving assembly 926 includes a receiving portion928 for receiving and engaging the members 914 or 970 of the deliverytool 902 and the chisel 960, respectively, as depicted in FIG. 9.

As can be understood from FIG. 12, in one implementation, thedecorticator 936 includes a tubular shaft portion 938, an abrasivedistal end 944, and a handle 940 at a proximal end. The tubular shaft938 may have an inner radius substantially equal to an outer radius ofthe shaft 976 of the place holding or guide chisel 974 of FIG. 15 andmay allow for sliding movement of the decorticator 936 along the lengthof the chisel shaft 976 and rotationally around the chisel shaft 976. Insome implementations, the inner radius of the tubular shaft 938 may beslightly or substantially larger than the outer radius of the shaft 976of the chisel 974 allowing for more freedom of movement of thedecorticator 936.

The abrasive distal end 944 of the decorticator 936 may include serratedteeth 946 as shown, or may include a more flat annular surface with agritty surface. In the implementation shown in FIG. 12, the distal endof the tubular shaft portion 938 is chamfered and the serrated teeth 946are located on the distal most end of the chamfered end allowing for amore directed and controllable decorticating process. As such, thedecorticator 936 shown is well suited for the intra facet processreflected by many of the implementations described herein. That is, thehuman anatomy of the cervical spine may be such that the lateral mass ofthe facet joints are not perpendicular to the surface of the facetjoint.

Additionally, to properly place the prongs 934 of the place holding orguide chisel 974 within the joint, the guide chisel 974 may bepositioned substantially parallel to articular surfaces of the facetjoint. As such, the place holding or guide chisel 974 may not bepositioned perpendicular to the lateral masses of the facet joints andmay actually be directed with a downward slope as it extends in thedistal direction. Where the decorticator 936 has a non-chamfered annularend, depending on anatomy, the decorticator 936 may be able to be placedin contact with the superior lateral mass, but may be unable to reach orcontact the inferior lateral mass. In the present implementation, thechamfered end of the tubular shaft portion 938 will allow the distal tipof the chamfered end to reach and decorticate the inferior lateral mass.This chamfered distal end may define an angle to the longitudinal axis.Additionally, the teeth 946 may be relatively large or they mayrelatively small and may extend along the full perimeter surface of thechamfered end rather being positioned solely at the tip of the chamferedend. Additionally, a beveled edge may run along the periphery of thechamfered end. That is, along the ovular shape created by the chamferedtubular shaft portion 938, the edge is beveled. As such, when the guidechisel 974 is inserted into the patient and/or when the decorticator 936is advanced along the chisel 974, the beveled edge may assist inavoiding tissue snags, and the decorticator 936 may be placed in contactwith the lateral mass of the facet joints in a much smoother process andmay avoid damage to neighboring tissues.

The handle 940 of the decorticator 936 may include a gripping surfacealong its peripheral edge and may sleevably receive the tubular shaftportion 938. The handle 940 may also include radially extending bores942 adapted to receive a gripping tool to provide for better control anda higher amount of torsional leverage when decorticating the lateralmasses of the facet joint or to allow for malleting in the longitudinaldirection of the decorticator 936 to cause forceful decortication of thelateral mass. The decorticator 936 may then be retracted, rotated to anew radial position, advanced, and struck again for additionaldecortication.

Referring to FIG. 13, in one implementation, the injector 948 includes alongitudinal delivery shaft 950 and a seating feature 952. Thelongitudinal delivery shaft 950 may have any cross-section and may havea cross-sectional size adapted to fit within the guide tube 904. Thelongitudinal shaft 950 may have an opening 956 on its distal end 954 fordirecting bone paste out the distal end of the shaft 950 allowing thepaste to flow into and/or over the facet joint and/or outward toward thelateral mass of a facet joint. The seating feature 952 may include amember 958 positioned around the shaft 950, which may be sized andshaped to abut the receiving portion 928 of the guide tube 904. Theinjector 948 may be sleevably inserted into the guide tube 904 andadvanced such that the distal end of the shaft 950 is positioned betweenthe prongs 934.

As can be understood from FIG. 14, in one implementation, the chisel 960includes a generally cylindrical cross-section forming a shaft 962,which may have a radius substantially equal to the inner radius of thetubular shaft portion 924 of the guide tube 904 allowing for slidableinsertion of the chisel 960 within the guide tube 904. Alternatively,the radius of the shaft 963 may be smaller than the inner radius of thetubular shaft 924 providing for more play and adjustability of thechisel 960 and the guide tube 904 relative to one another. The chisel960 may include a single or doubly chamfered tip 972 at a distal end ormay have a coped distal end or a combination of coping and chamfering.The tip 972 may include a roughened surface on one or more sides to aidin anchoring or docking the chisel in the facet joint. Additionally,this roughened surface may allow for roughening or decorticating theinner surfaces of the facet joint. The tip 972 may have a length adaptedto extend substantially across the facet joint.

The chisel 960 may further include a handle assembly 964 may include amember 970 positioned around the shaft 962, which may be sized andshaped to abut the receiving portion 928 of the guide tube 904. Thechisel 1008 may also include a longitudinally extending lumen 968 and amalleting head 966.

Turning to FIG. 15, in one implementation, the placing holding or guidechisel 974 includes a shaft 976 and a distal tip 978, which may includea tip the same or similar to the chisel 960. For example, the chisel 974can include a coped and/or chamfered tip. Additionally, the chisel 974can include ridges. Additionally, the chisel 974 can include aradiopaque portion on the shaft 976 adapted to allow recognition of thelocation of the chisel 974 while avoiding occlusion of the lateral view.The radiopaque portion can include a straight, round, square, or othershaped piece of material positioned near the distal end of the chisel974 for locating the distal end. As also shown, the proximal end of thechisel 974 can include a hole extending transversely there through. Thehole can adapted to receive a transverse rod or shaft extending into thehole and/or through the hole. The rod or shaft and the chisel 974 canform a T-grip or L-shaped grip for use in pulling on the chisel 974 forremoval.

In one implementation, the place holding chisel 974 can be used as aplace holder without occluding the lateral view of a chisel and deliverytool positioned in a contralateral facet joint. That is, upon placementof the chisel 960 and the guide tool 904 in a first facet joint, thechisel 960 may be removed and replaced with the place holding chisel 974where the prongs 934 of the guide tube 904 maintain the position of thesystem 900. The guide tube 904 may also be removed and reassembled withthe chisel 960 once the place holding chisel 974 is properly positioned.The guide tube 904 and chisel 960 may then be inserted into thecontralateral facet joint or second joint. By replacing the chisel 960in the first joint with the place holding chisel 974, the location ofthe chisel 960 and guide tube 904 in the second joint may be morereadily ascertainable using lateral fluoroscopy. That is, if aradiopaque chisel or delivery device was left in place in the firstjoint, the fluoroscopic view of the contralateral facet joint would berelatively occluded. Upon placing the guide tube 904 properly in thesecond facet joint, the procedure above may continue. Upon completingtreatment of the second facet joint, the guide tube 904 may be sleevedover the place holding chisel 974 still positioned in and holding theplace in the first facet joint and the first facet joint may then betreated with the above procedure. It is noted that initial placement ofthe guide tube 904 can be conducted with the place holding chisel 974rather than the chisel 960 to avoid having to replace the chisel 960.

Referring to FIG. 16, in one implementation, the malleting tool 980 caninclude a longitudinally shaped shaft with a U-shaped decorticatorinterface 984 at one end and a chamfered tip 982 at the other end. Thedecorticator interface 984 can be adapted for positioning around theguide tube 904 in a position just proximal to a malleting element of thedecorticator 936. The u-shape of the decorticator interface 984 mayallow the malleting tool 980 to be placed in position from the side ofthe guide tube 904 and selectively used as required to forcibly advancethe decorticator 936.

The chamfered end of the tool 982 can be held in position while the usermallets near the decorticator interface end causing the interface 984 tocontact the malleting element on the decorticator 936. The decorticator936 may then be retracted, rotated to a new radial position, advanced,and struck again for additional decortication. The malleting tool 980may rotate with the decorticator 936 or it may remain in a positionconvenient for malleting. In addition to malleting, the malleting tool980 can be used to assist in separating several tools. That is, in somecases, the handles of a given tool piece can be difficult to separatefrom receiving portion. The chamfered tip 982 can be used to wedgebetween a given handle and the receiving portion to assist in separatingthe devices.

Other implementations of a distraction system 900 can be configured withalternative retaining and deployment (release or eject) methods, such asscrew drives, latches, snaps, cams, adhesives, magnets, or the like.

The delivery system components depicted in FIGS. 9-16 can be used tominimally invasively implant any of the implants 100 depicted in FIGS.1A-8D in a spinal facet joint that is the target of treatment. Forexample, in one embodiment, a percutaneous or minimally invasiveincision is made in the posterior region of the neck to lead to thetarget facet joint. The access chisel 974 depicted in FIG. 15 is routedthrough incision under fluoroscopic guidance until the tapered distaltip 978 resides in the target facet joint and the chisel shaft 976extends out of the patient via the incision. With the access chisel 974so positioned, the outer decorticator 936 of FIG. 12 can be grasped anddistally routed over the access chisel 974 such that the chisel shaft976 is received in the lumen that extends longitudinally through theouter decorticator 936. With the distal decorticating end 946 of theouter decorticator 936 abutting against one or more lateral massesadjacent the target facet joint, the outer decorticator 936 can berotated about the chisel shaft 976 to decorticate the bone surfaces ofthe lateral masses adjacent the target facet joint. Once decorticationof the lateral masses has been sufficiently achieved, the decorticator936 can be removed from about the chisel shaft 976 and from the patient.

With the place holding or access chisel 974 so positioned, the guidetool 904 of FIG. 11 is grasped and distally routed over the chisel 974such that the chisel shaft 976 is received in the guide tool lumen thatextends longitudinally through the guide tool shaft 924. The taperedforked distal end 907 of the guide tool 904 is distally advanced throughthe incision and along the chisel shaft 976 until the tapered forks 934of the guide tool 904 are positioned inside the target facet joint, thechisel tapered distal tip 978 being located between the pair of forks934 of the guide tool distal end 907, the guide tool shaft 924 extendingout of the patient via the incision.

With the guide tool 904 so positioned, the place holding or accesschisel 974 can be withdrawn out of the guide tool lumen and out of thepatient, leaving the guide tool tapered forked distal end 907 residingin the target facet joint and the guide tool shaft extending out of thepatient. The decorticating chisel 960 of FIG. 14 can then be distallyrouted through the lumen of the guide tool 904 to place the tapereddecorticating distal end 972 of the chisel 960 between the guide toolforks 934 located in the target facet joint space. The decorticatingchisel 960 can then be displaced distal-proximal to cause the tapereddecorticating distal end 972 of the chisel 960 to remove the cartilageof the target facet joint space located between the guide tool forks 934and further decorticate any associated bone surfaces of the target facetjoint space. Once the target facet joint space surfaces have beenprepped with the decorticating chisel 960, the chisel 960 can be removedfrom the lumen of the guide tool 904 and the patient.

The implant 100 is coupled to, and supported off of, the distal end 906of the implant delivery tool 902 of FIG. 10. As discussed above, thecoupling of the implant delivery tool distal end 906 with the implant100 may be achieved via interference fit and/or threaded engagement.With the implant supported off of the distal end 906 of the implantdelivery tool 902 in a manner similar to that depicted in FIG. 10, theimplant 100, and the delivery tool shaft 910 on which the implant 100 issupported, are distally routed through the lumen of the guide tool 904until the implant 100 and the delivery tool distal end 906 are locatedin the target facet joint space between the pair of forks 934 of theguide tool distal end 907, the delivery tool 902, the guide tool 904 andthe implant 100 being coupled together as depicted in FIG. 9. With theimplant 100 so positioned in the target spinal facet join space, themember 916 may be used to deposit the implant 100 into the target spinalfacet joint space by either plunging and/or threadably decoupling theimplant 100 from the delivery tool distal end 906 via correspondingmanipulation of the member 916 via its handle 920. Once the implant 100is decoupled from the delivery tool 902 and deposited into the facetjoint space, the delivery tool 902 can be withdrawn from the guide tool904, which is left in place with its forked distal end 907 occupying thefacet joint space and the implant 100 being located between the forks934 of the guide tool 904.

With the implant 100 and forks 934 so positioned in the facet jointspace and the guide tool shaft 924 extending from the patient, bonegrowth promoting paste may be plunged down the lumen of the guide tool904 via the shaft 950 of the injector 948 being distally displaced downthe lumen to cause the bone paste to exit the distal end 907 of thedelivery tool 904 and extend about the implant 100 occupying the spinalfacet joint space. The injector 948 and guide tool 904 can then bewithdrawn from the patient, the implantation of the implant 100 in thefacet joint having been completed. The process can then be repeated foranother facet joint if needed.

FIGS. 17-18 outline an embodiment of a method of implanting anembodiment of an implant in a spinal facet joint space. This method, andtools employed with this method embodiment, will now be discussed inreference to the flow chart depicted in FIGS. 17-18.

FIG. 19A is a side view of a place holding or access chisel similar tothat already described above, and FIG. 19B is an enlarged perspectiveview of a distal portion of the chisel of FIG. 19A. As illustrated inFIGS. 19A-19B, the place holding or access chisel 5200 may have agenerally cylindrical cross-section forming a shaft 5202. The shaft 5202may have a radius substantially equal to the inner radius of a tubularshaft portion 5302 of a guide tube or tool 5300 similar to that alreadydescribed above and again shown in FIG. 21. Because of thisrelationship, the access chisel 5200 can by slidably inserted within theguide tool 5300. The access chisel can include a single or doublychamfered tip 5204 at a distal end of the shaft 5202. The access chiselmay include radiolucent markers or holes 5208 extending through theshaft perpendicular to a longitudinal axis that extends along the lengthof the shaft. The radiolucent markers 5208 assist with confirming theappropriate depth of placement of the access chisel relative to thefacet joint when used in conjunction with lateral fluoroscopy. Asdepicted in FIG. 19B, the tip 5204 of the access chisel 5200 can includea notch 5210 in the chamfered tip 5204 wherein a bore can extend throughthe chisel shaft 5202 to allow the insertion of a needle, guidewire orother medical device.

In some embodiments, the faces of the tip 5204 contain ridges, and, inother embodiments, the faces are ridgeless. The faces 5212 of the tip5204 of the access chisel 5200 in the embodiment of FIG. 19A-B areridgeless. In such an embodiment, resistance experienced by a userattempting to access a facet joint with the tip of the chisel 5200 maybe minimized.

It is noted that the place holding or access chisel 5200 can be insertedinto the facet joint prior to the insertion of a guide tool 5300. Theaccess chisel 5200 may distract the facet joint by inserting the accesschisel 5200 in the joint and tapping, hammering, or otherwise advancingthe access chisel 5200 into the joint. After the access chisel 5200distracts the facet joint, the guide tube 5300 may be sleeved over theaccess chisel with the forks 5304 of the guide tube 5300 inserting intothe facet joint, whereby the access chisel 5200 may be removed.

FIG. 20 is a side view of the access chisel of FIG. 19A extendingthrough and a guide tube or tool, and FIG. 21 is a side view of theguide tool or tube of FIG. 20. As illustrated in FIGS. 20-21 and assimilarly described above, the guide tube 5300 may include a receivingassembly 5306 at a proximal end, anchoring forks 5304 at a distal end,and a generally tubular shaft 5302 defining a longitudinal axis andextending between the receiving assembly 5306 and the anchoring forks5304. As discussed previously, after the access chisel 5200 is insertedinto the facet joint, the guide tube 5300 may be sleeved over the accesschisel 5200. The guide tool forks 5304 support the loading forceformerly on the access chisel 5200 such that the access chisel 5200 maybe slidably removed from the guide tube 5300. Such variations of theguide tool 5300 are discussed above.

FIG. 22 is a side view of a decorticating chisel with a rasp end beingintroduced into a proximal end of the guide tool 5300 of FIG. 21. FIG.23 is a side view of the decorticating chisel of FIG. 22 fully insertedin the guide tool 5300, wherein the devices so coupled together can beconsidered to form a driver assembly. As indicated in FIGS. 22-23, afterremoval of the place holding or access chisel 5200 from the guide tubeor tool 5300, a decorticating chisel 5400 or other suitable chisel maybe inserted into the delivery device to decorticate the articularsurfaces of the facet joint by manipulating the decorticating chisel5400 within the joint. This may include tapping the decorticating chisel5400 with a device such as a hammer, mallet, or other instrument toadvance the distal tip 5402 of the decorticating chisel 5400 and mayalso include moving the proximal end of the decorticating chisellaterally from side to side, up and down, or rotationally, todecorticate the joint surface. The decorticating chisel 5400 may then betapped into place anteriorly such that it extends substantially throughthe joint. Fluoroscopy from one or more directions may be used to verifythe location of the decorticating chisel 5400. The decorticating chisel5400 may then be removed from the facet joint.

FIGS. 24 and 25 are perspective views of various distal tip portions ofthe decorticating chisel 5400 positioned between distal laterally ortransversely spaced-apart forks of the distal end of the guide tool5300. As shown in FIGS. 24-25, the surfaces of the tip 5402 of thedecorticating chisel 5400 include a series of ridges 5406. The ridges5406 can be relatively sharp and can aid the user in roughening ordecorticating the facet surfaces as the decorticating chisel 5400 isinserted and removed from a facet joint. The ridges 5406 can include apattern adapted to maintain the chisel's position in a facet joint. Insome embodiments, the ridges 5406 can include a sloping distal face anda relatively vertical (e.g., perpendicular to axis of chisel 5400)proximal face. As the decorticating chisel 5400 is advanced, thesurfaces in contact with the decorticating chisel 5400 may ride up alongthe sloping distal face until the decorticating chisel 5400 ispositioned. The relatively sharp apex of the ridges 5406 formed by thesloping distal face and relatively vertical proximal face can functionto hold the decorticating chisel in place. Moreover, the ridges 5406 canbe arranged in a surface pattern suitable for holding the decorticatingchisel 5400 in place. In one embodiment, referring to FIG. 25, theridges 5406 can include a chevron pattern. Referring to FIG. 24 theridges 5406 can include a pattern of rows of steps that extend along theincline of the face wherein a recessed groove is positioned between therows. Other patterns such as straight rows, diagonal rows, wavy rows, orother alternative patterns can be included.

FIG. 26 is a side view of a driver device or delivery tool supportingthe implant from a distal end of the delivery tool, the delivery toolbeing positioned to be inserted in a proximal portion of the guide tool.FIG. 27 is a side view of the driver device fully received in the guidetool. FIG. 28 is an enlarged perspective view of a distal end of thedriver device, wherein a threaded male member is visible for threadablycoupling with the implant. FIG. 29 is a perspective view of the implantwherein a threaded female opening is depicted in a proximal face of theimplant.

As shown in FIG. 26 and as similarly described above, the driverassembly or delivery tool 5500 includes a handle 5501, an implant shaft5508, an implant retainer 5506, and an internal actuator 5502. Aninternal rod 5510, which is coupled to the internal actuator 5508 andthe implant retainer 5506 and illustrated in FIG. 28, transfers theforce from the internal actuator 5502 to the implant retainer 5506. Asdepicted in FIGS. 26-27, the driver assembly or delivery tool 5500 isslidably received in the guide tool 5300 for inserting the implant 5504into the patient's facet joint.

As can be understood from FIG. 28, the distal end of the driver assembly5500 includes an internal rod 5510 and an implant retainer 5506 at thedistal end of the internal rod 5510 adapted to secure an implant duringinsertion and distraction of the implant into the joint. Further, insome embodiments, the distal end or face of the driver assembly 5500includes implant receiving notches 5512 for rotationally orienting andsecuring the implant relative to the driver assembly.

The internal rod 5510, shown in FIG. 28, may be positioned within theshaft 5508 and may extend from the handle 5501 to the distal end of thelongitudinal shaft 5508. The implant retainer 5506 includes anengagement feature 5514 at its distal end for engaging and holding theimplant 5504. This engagement feature 5514 may be a thread feature suchas, for example a male-end of a screw. In the embodiment where theengagement feature 5514 is a thread feature, the exact type andcharacteristics of the thread feature can vary accordingly so as toadequately retain an implant during insertion and distraction of a facetjoint. The engagement feature 5514 may be any shape and provide for anyengagement known in the art capable of transmitting longitudinal and/orrotational forces from the internal rod 5510 to engage correspondingfeatures on an implant 5504. For example the engagement feature caninclude a keyed shaft and coupler, splined shaft and coupler, etc.

Those skilled in the art would appreciate that although the variousembodiments depict the engagement feature 5514 as a male-end threadfeature at the distal end of the internal rod 5510 and a correspondinginternal female-end receiving thread featured implant, the tool 5000 canfunction similarly by including a male-end thread feature on theproximal end of an implant and a corresponding internally threadedfemale receiving feature on a distal end of the internal rod 5510.

As depicted in FIGS. 28-29, the distal end of the driver assembly 5500includes implant receiving notches 5512 for rotationally orienting andsecuring the implant relative to the driver assembly 5500. The implant5504 includes corresponding implant knobs 5518 that friction fit intothe implant receiving notches 5512 of the driver assembly 5500.Additionally, the implant 5504 is generally rectangular and cage-shaped,with opposing upper and lower faces that include teeth 5504 that extendoutward from the upper and lower planar faces in a general spaced-outsaw tooth orientation.

In one particular embodiment, as depicted in FIG. 29, the implant 5504includes an internally threaded female receiving feature 5516 that isadapted to matingly receive the engagement feature 5514, which in thisembodiment is a thread feature. The implant knobs 5518 aid in resistingrotational movement of the implant relative to the driver assembly 5500when the knobs 5518 are matingly received in the implant receivingnotches 5512. A surgeon or surgical assistant may place the implantknobs 5518 in the receiving notch 5512, prior to insertion into theguide tube 5300, so that the as the engagement features 5514 of theimplant retainer 5506 engage the implant, the implant 5504 remains aconstant orientation relative to the driver assembly 5500.

As indicated in FIG. 36, which is a perspective view of a proximal ortrailing end of an implant 5504, in one embodiment, the implant 5504 mayhave other features for preventing rotational displacement between theimplant and the driver assembly 5500. For example, instead of having themale/female pin/recess 5518/5512 arrangement between the implant anddistal end of the driver assembly depicted in FIGS. 197-198, the implant5504 could include slots 5518 extending along at least part of eachlateral side surface from the proximal trailing face of the implant5504, as depicted in FIG. 36. Corresponding arms or pins (not shown, buteasily visualized and understood by someone of ordinary skill in theart) could distally extend from the distal leading face of the distalleading end of the driver assembly 5500 to be matingly received in theslots 5518 depicted in FIG. 36. The arms or pins being received in theslots 5518 of FIG. 36 would prevent rotation of the implant relative tothe driver assembly.

FIG. 30 is a perspective view of the distal end of the driver assembly5500 approaching the proximal end of the implant to achieve couplingbetween the two. FIG. 31 is a perspective view of the distal end of thedriver assembly coupled to the proximal end of the implant. FIG. 32 is aperspective view of the guide tool, driver assembly, and implant whereinthe implant is coupled to the distal end of the driver assembly andnestled between the forks of the guide tool. FIG. 33 is the same view asFIG. 32, except the driver assembly has been decoupled from the implantand withdrawn from within the guide tube. FIGS. 34 and 35 arelongitudinal cross sections of the arrangement depicted in FIG. 32.

In certain embodiments, in reference to FIGS. 30-35, the implantretainer 5506 is such that rotation of the internal actuator 5502 causesthe implant retainer 5506 and the corresponding engagement feature 5514to rotate and translate proximally and/or distally, depending on thedirection of rotation of the internal actuator 5502. As such, to engagethe implant 5504 with the driver assembly 5500, the implant knobs 5518are engaged with the implant receiving notches 5512 and the internalactuator is rotated such that the engagement feature 5514 that wasrecessed to a point to allow the implant knobs 5518 to be engaged withthe notches 5512 is now rotating and translating out of its recessedstate and into engagement with the female receiving portion 5516 of theimplant 5504. Correspondingly, after the implant is inserted into thepatient's facet joint, the internal actuator is rotated in an opposingdirection and the engagement feature 5514 of the implant retainer 5506therefore rotates and translates distally back into a recessed statewithin the shaft 5508 of the driver assembly 5500. In this way, theengagement feature 5514 of the implant retainer 5506 “backs out” andreleases the implant 5504 in the facet joint.

In another embodiment, also with reference to FIGS. 30-35, the implantretainer 5506 is such that rotation of the internal actuator 5502 onlycauses rotational motion of the implant retainer 5506 and thus theengagement feature 5514 (i.e., the implant retainer 5506 does nottranslate proximally and distally to a recessed and non-recessed state).As such, to engage the implant 5504 with the driver assembly 5500, theimplant 5504 is positioned adjacent the engagement features 5514 and theinternal actuator is rotated such that the engagement feature rotatablyengages with corresponding internally threaded feature 5516 of theimplant 5504 and the implant retainer 5504 thereby “pulls” the implant5504 into engagement with the implant retainer 5504. Note that in thisembodiment, the implant knobs 5518 are engaged with the implantreceiving notches 5512 by the “pulling” together of the implant 5504 bythe implant retainer 5506. Once the implant is inserted into thepatient's facet joint, the internal actuator 5502 is rotated in anopposing direction and the engagement feature 5514 of the implantretainer 5506 therefore rotates and “pushes” the implant 5504 out ofengagement with the implant retainer 5506.

Referring to FIGS. 31-33, once the implant 5504 is coupled to the driverassembly 5500, the implant 5504 can optionally be packed with autograft(i.e., autologous bone) before implantation into the patient's facetjoint. The implant 5504 and driver assembly 5500 is slidably insertedinto the guide tube 5300. In order to fully “seat” the implant into thedelivery device 5300 and in the facet joint, malleting may be requiredsince the upper and lower faces of the cage-shaped implant 5504 canprotrude above the forks 5304, which were providing the holding forcefor the distraction.

FIGS. 34-35 depict cross-sectional views of the tool 5000 and implant5504. Engagement of the implant 5504 with the engagement features 5514is clearly visible, as is the nesting relation between the forks of theguide tube 5300 and the driver assembly 5500 and between the internalrod 5510 and the driver assembly 5500.

Referring to FIGS. 17-18, a method of performing an interbody fusion caninclude inserting an access chisel into a joint between vertebral bodiesof the spine to provide for initial distraction of the facet joint(5102), confirming the depth and placement of the access chisel usingradiolucent markers or holes in the shaft of the access chisel (5103),inserting a guide tool over the access chisel to maintain the initialdistraction (5104), removing the access chisel from the guide tool(5106), inserting a decorticating chisel into the guide tool fordecorticating the facet surface (5108), decorticate and prepare thesuperior and inferior surface of the joint with the distal surfaces ofthe decorticating chisel (5110), removing the decorticating chisel fromthe guide tool (5112), attaching an implant to a driver assembly viathread feature on an implant retainer, the implant having correspondingfeatures that matingly receive the thread feature of the implantretainer (5114), packing the implant fenestrations with autograft(5116), inserting the implant and driver assembly into the guide tooland into the joint, whereby malleting may be required to fully engagethe implant with the joint, the implant having teeth adapted to engagethe surfaces of the joint (5118), and releasing of the implant from thedriver assembly by decoupling the threaded implant retainer and theimplant, thereby leaving the implant in place in the joint (5120).

For a further discussion regarding delivery systems and methodology, seeU.S. patent application Ser. No. 12/653,283, which was filed on Dec. 10,2009 and entitled “Verbal Joint Implants and Delivery Tools.”

The description above includes example systems, methods, techniques,instruction sequences, and/or computer program products that embodytechniques of the present disclosure. However, it is understood that thedescribed disclosure may be practiced without these specific details.

It is believed that the present disclosure and many of its attendantadvantages will be understood by the foregoing description, and it willbe apparent that various changes may be made in the form, constructionand arrangement of the components without departing from the disclosedsubject matter or without sacrificing all of its material advantages.The form described is merely explanatory, and it is the intention of thefollowing claims to encompass and include such changes.

While the present disclosure has been described with reference tovarious embodiments, it will be understood that these embodiments areillustrative and that the scope of the disclosure is not limited tothem. Many variations, modifications, additions, and improvements arepossible. More generally, embodiments in accordance with the presentdisclosure have been described in the context of particularimplementations. Functionality may be separated or combined in blocksdifferently in various embodiments of the disclosure or described withdifferent terminology. These and other variations, modifications,additions, and improvements may fall within the scope of the disclosureas defined in the claims that follow.

What is claimed is:
 1. An implant for a spinal facet joint, the implantcomprising: a distal leading portion having a distal surface generallyopposite a proximal surface of a proximal trailing end; a first sidehaving a first side surface generally opposite a second side having asecond side surface; a first face having a first surface and a secondsurface with a second face, the first and second faces extending betweenthe distal leading portion and the proximal trailing end, each of thefirst and second surfaces having a plurality of teeth, wherein one ormore teeth of the plurality of teeth comprises an inner side surfacegenerally opposite an outer side surface, the outer side surface isadjacent to a respective side surface of the first or second side and atleast a portion of the inner side surface is generally perpendicular tothe first surface of the first face or the second surface of the secondface; one or more windows defined in the first surface generallyopposing one or more windows defined in the second surface; and one ormore side windows defined in the first side surface generally opposingone or more side windows defined in the second side surface, the windowsand side windows providing at least partial access to an interior of theimplant.
 2. The implant of claim 1, wherein the plurality of teethdefines at least one ridge extending perpendicularly from each of thefirst and second surfaces along at least a portion of the length of thefirst and second surfaces, wherein one or more teeth of the plurality ofteeth comprises a leading distal face, a trailing proximal face, and atip formed at an intersection between the leading distal face and thetrailing proximal face.
 3. The implant of claim 2, wherein the trailingproximal face has a slope that is greater than a slope of the leadingdistal face.
 4. The implant of claim 1, wherein the plurality of teetheach have a pyramidal shape with a rectangular base that is generallyparallel to a respective surface of the first face and the second face.5. The implant of claim 1, wherein the plurality of teeth form one ofsmall pyramids or large pyramids.
 6. The implant of claim 1, wherein theplurality of teeth are arranged in rows, a first row of the teethabutting a second row of the teeth.
 7. The implant of claim 1, wherein aplurality of grit particles extend generally perpendicularly from arespective surface of the first face and the second face and the gritparticles are randomly adhered to the surfaces of the first face and thesecond face.
 8. The implant of claim 1, wherein a plurality of pitsextend generally perpendicularly into a respective surface of the firstface and the second face.
 9. The implant of claim 8, wherein theplurality of pits cover a respective surface of the first face and thesecond face in a random orientation.
 10. The implant of claim 8, whereinthe plurality of pits are achieved as a result of surface treating thesurfaces of the first face and the second face.
 11. The implant of claim1, wherein the windows and the side windows are rectangular in shape.12. The implant of claim 1, wherein the windows are circular in shape.13. The implant of claim 1, wherein the trailing proximal face has aslope that is less than a slope of the leading distal face.
 14. Theimplant of claim 1, wherein the trailing proximal face has a slope thatis approximately the same as a slope of the leading distal face.
 15. Theimplant of claim 1, wherein the spinal facet joint is a cervical facetjoint.
 16. A spinal facet cage implant for implantation in a spinalfacet joint, the implant comprising: a distal leading portion having adistal end surface generally opposite a proximal end surface of aproximal trailing end; a first side having a first side surfacegenerally opposite a second side having a second side surface; a firstface having a first surface that is generally opposite a second surfaceof a second face, the first and second faces extending between at leasta portion of the distal leading portion and the proximal trailing end,the first and second surfaces having a plurality of teeth, wherein oneor more teeth of the plurality of teeth comprises an inner side surfacegenerally opposite an outer side surface, the outer side surface isadjacent to a respective side surface of the first or second side and atleast a portion of the inner side surface is generally perpendicular tothe first surface of the first face or the second surface of the secondface; a set of distal windows positioned near the distal leading portionand including a distal window defined in the first surface of the firstface and a distal side window defined in the side surface of the firstside, the set of distal windows providing access to a distal chamber inan interior of the implant; and a set of proximal windows positionednear the proximal trailing end and including a proximal window definedin the first surface of the first face and a proximal side windowdefined in the side surface of the first side, the set of proximalwindows providing access to a proximal chamber in an interior of theimplant.
 17. The implant of claim 16, wherein the spinal facet joint isa cervical facet joint.
 18. An implant for a spinal facet joint, theimplant comprising: a distal leading portion having a distal surfacegenerally opposite a proximal surface of a proximal trailing end; afirst side having a first side surface generally opposite a second sidehaving a second side surface, the first side and the second side adaptedto interact with opposed prongs of a delivery tool; and a first facehaving a first surface and a second surface with a second face, thefirst and second faces extending between the distal leading portion andthe proximal trailing end, each of the first and second surfaces havinga plurality of teeth, wherein one or more teeth of the plurality ofteeth comprises an inner side surface generally opposite an outer sidesurface, the outer side surface is adjacent to a respective side surfaceof the first or second side and at least a portion of the inner sidesurface is generally perpendicular to the first surface of the firstface or the second surface of the second face.
 19. The implant of claim1, wherein the implant is formed of a bone or bone substitute material.20. The implant of claim 18, wherein the implant is formed of a bone orbone substitute material.